I have been reading the forums here for about a year. I recently decided to take the plunge into a dual fuel Keystoker KA6 boiler. I just received me first load of coal for it and notice what appears to be a decent amount of stones in the coal. It is rice sized coal. I have attached a couple pictures and would appreciate feedback on if this is normal. If it is not normal, do you think it would mess up the keystoker by using this coal? The stones seems to be the same uniform size as the coal.

Need less to say, if it is not normal, I am also not happy having paid for a bunch of rocks either

I have never heard anyone mention stones of any kind on the forums so seeing this is making me leery.

If all of that is ash and there is a decent amount, I am guessing that will cut down on the BTU of the coal since ash obviously doesn't burn. Given that this must be bottom of the bucket coal, what would it normally go for in PA as a pickup without delivery charges?

I expect you are right too, I took about ten of them out, tapped them with a small hammer today and they break apart quite easily, not like solid rocks. They also weigh about the same as the coal, not as heavy as normal rocks.